JPH06275514A - Resist pattern forming method - Google Patents

Abstract

PURPOSE:To enable fine resist patterns in high density or high aspect ratio to be formed without running short of the patterns. CONSTITUTION:A resist pattern 2 exposing specific patterns, after it is developed, is rinsed and then the whole surface thereof is irradiated with sensitizing beams (a) before a rinsing solution 5 runs away to be dried up later so as to complete the resist patterns 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist pattern forming method capable of effectively preventing collapse of a resist pattern.

[0002]

2. Description of the Related Art With the demand for higher integration of ULSI, formation of an extremely fine resist pattern is required. Currently, formation of a resist pattern having a minimum dimension of 0.2 to 0.3 μm is being actively studied, and in leading-edge research, 0.1
Some target μm. In addition, as another flow, there is a demand for a thick and fine pattern.
For example, in order to manufacture a micromachine, technological development for forming a resist pattern having an extremely high aspect ratio using a resist having a large film thickness (for example, 100 μm) is also under way.

As a method for exposing a resist pattern, g
Various sources such as ultraviolet rays such as X rays and i rays, excimer laser rays such as KrF and ArF, far ultraviolet rays such as Xe-Hg lamps, electron rays, charged particles, and X rays are used. A wet developing method using a liquid developer is mainly used. On the other hand, some dry development methods that utilize silylation reactions and do not require liquid processing have been investigated, but low throughput, high processing equipment cost, and defects due to dust, contamination, and plasma damage. Due to its high rate of occurrence, the dry development method has not come into full use. Therefore, wet development has the advantage that the process is simple,
Since the cleaning process involves cleaning with a rinse solution, it will be used in the future and studies are underway.

FIG. 4 shows a conventional method of forming a resist pattern. As shown in FIG. 3A, the resist 2 is applied on the substrate 1. As shown in FIG. 3B, a mask 3 is used to expose a desired pattern. As for the exposure,
Ultraviolet light, far-ultraviolet light, X-ray, electron beam, charged particle beam and the like are used. Next, as shown in FIG. 3C, the resist 2 is dipped in the developing solution 4. The resist pattern 2a is formed by utilizing the difference in dissolution rate of the resist 2 with respect to the developing solution 4 in the exposed area and the non-exposed area. Then, as shown in FIG. 3D, the developing solution 4 and the resist 2 dissolved in the developing solution 4 are washed away with the rinse solution 5. As the rinse liquid 5, water at 20 to 25 ° C. is generally used. Further, as shown in FIG. 7E, the rinse liquid 5 is dried to complete the resist pattern 2a. In this drying process, spin drying in which a wafer is rotated at high speed is usually used.

[0005]

The resist pattern formed by the above method has a problem that a fine pattern (for example, 0.2 μm) collapses although the pattern collapse does not occur in a large resist pattern. Further, the pattern collapse occurs even in a pattern having a high aspect ratio (resist height / resist pattern width). As shown in FIG. 5, these pattern collapses are such that adjacent patterns 2a are densely gathered and lean against each other.

Such pattern collapse means that a desired resist pattern cannot be formed, which directly leads to a reduction in yield and reliability of products to be manufactured. In order to integrate elements at a high density or to make a compact product, a fine pattern is required, and it is necessary to arrange fine patterns at fine intervals. It becomes impossible to make highly integrated or compact products.

The present invention was conceived in view of the above problems of the prior art. A method for effectively preventing pattern collapse at the time of forming the resist pattern has been studied, and a particularly dense fine resist pattern or a high aspect ratio can be obtained. Another object of the present invention is to provide a resist pattern forming method capable of forming a different resist pattern without the pattern collapse.

[0008]

Therefore, according to the present invention, a resist pattern is formed by exposing a resist to a desired pattern, developing the resist, and then rinsing and drying the rinse liquid to form a resist pattern. The method is basically characterized in that a treatment for increasing the strength of the resist in a liquid is performed between the developing treatment and the rinsing treatment or during the rinsing treatment. An example of the process for increasing the strength of the resist is a process for increasing the degree of crosslinking of the resist. Here, the strength of the resist refers to the degree of difficulty of deformation when an external force is applied and the strength of the resist breaking strength against the external force. That is, it is the strength against deformation including elastic deformation and plastic deformation.

In the present invention, the treatment for increasing the degree of crosslinking of a resist in a liquid means, when a negative resist is used as the resist, irradiating the resist with light. When the resist is a chemically amplified resist, it is to raise the liquid temperature to a temperature that promotes crosslinking, and when the resist is an acid-catalyzed crosslinking-accelerating resist, it can be treated in an acidic liquid. In this case, it is more preferable to raise the liquid temperature to a temperature that promotes cross-linking and perform the treatment in an acidic liquid. The above is the processing when a cross-linking type resist is used, but also for a positive type resist based on a resin based on a benzene ring, for example, a positive type resist based on a novolac resin or a polyhydroxystyrene resin. Similar processing can be performed. That is, in the case of using the resist, the base resin is crosslinked by irradiating strong ultraviolet light or far ultraviolet light,
The resist strength will increase.

In addition to such a treatment for increasing the degree of crosslinking of the resist, as a second invention, a treatment for increasing the degree of polymerization of the resist in a liquid is performed between the developing treatment and the rinsing treatment or during the rinsing treatment. This makes it possible to increase the strength.

[0011]

It is clear that the collapse of the resist pattern occurs in the steps from the dropping of the developing solution to the drying of the rinse solution.
However, it was not clear in which process it occurred. As a result of detailed investigation, it was found that when the rinse liquid is dried, the surface tension of the rinse liquid exerts a suction force between the resist patterns to cause pattern collapse. Therefore, the pattern collapse does not occur before the rinse liquid is dried. In the case of a cross-linking resist or a positive resist based on a novolac resin, the strength of the resist increases as the crosslinking rate is improved, and the strength also increases by increasing the polymerization degree of the other resist, Pattern bending and pattern bending are less likely to occur. Therefore, in the present invention, after the resist pattern is formed, the degree of crosslinking or the degree of polymerization is increased in the liquid to increase the pattern strength, and the pattern tension is prevented so as to withstand the surface tension due to the rinse liquid drying. Since the process for increasing the strength is performed after the development (after the pattern formation), the process does not cause the deterioration of the pattern resolution or the defective shape.

[0012]

EXAMPLES Specific examples of the present invention will be described in detail below. FIG. 1 shows a resist pattern forming step performed as an embodiment of the present invention. In this step, the resist pattern forming step is basically carried out in substantially the same step as the step shown in FIG. I am doing it.

That is, as shown in FIG. 1A, a resist 2 having a thickness of 1 μm is applied on a substrate 1 and then heat-treated. In the present embodiment, as the resist 2, a cross-linking type negative resist (a material of which azide is a main component of a cross-linking agent is a typical example) is Hitachi Chemical's BLESTIV-7S.
(Trade name) was used. Then, as shown in FIG.
X-rays are irradiated using the mask 3 to expose a desired pattern. The exposure light is not limited to X-rays as long as it is light that the resist sensitizes, and ultraviolet light, far ultraviolet light, electron beam,
Exposure by a charged particle beam or the like may be used. Thereafter, as shown in FIG. 6C, the resist 2 is developed using a 2.38% tetramethylammonium hydroxide aqueous solution 4. Then, as shown in FIG. 3D, the water is rinsed with a rinsing liquid 5
As a rinse, the developer 4 and the resist 2 dissolved in the developer 4 are washed away. Before draining the water,
As shown in FIG. 6E, the entire surface was exposed to light. Here, an Hg-Xe lamp was used to irradiate light ranging from ultraviolet light to far ultraviolet light. However, this is an implementation condition, and there is no problem as long as it is photosensitive, and for example, i-line (wavelength 36
5 nm). Finally, spin drying is performed to remove the rinse liquid 5 as shown in FIG.

In the experiment carried out in this embodiment, the 0.2 μm line & space pattern collapsed in the usual method in which the entire exposure of light was not performed.
In the method of the present invention in which the entire surface was irradiated as described above, pattern collapse did not occur.

Next, in order to verify another embodiment capable of improving the cross-linking ratio of the resist, the present inventors have shown in FIG.
A resist pattern forming process including the steps shown in FIG. That is, the processes of FIGS. 9A to 9D are the same as those of the first embodiment. However, as the resist 2,
Any type of resist may be used as long as the photosensitive portion is thermally crosslinked. In this example, a chemically amplified negative resist SAL601 (trade name) manufactured by Shipley Co. was used. Then, before the rinse liquid 5 was dried, the rinse liquid 5 was heated as shown in FIG. Although the temperature is heated to 90 ° C. here, it is more preferable to set the temperature to about 120 ° C. while applying pressure to further promote crosslinking. It was also effective to heat while irradiating with light. In this case, it is preferable to use ultraviolet light to far ultraviolet light as the photosensitivity. Finally, spin drying was performed to remove the rinse liquid 5 as shown in FIG. 3F to form a resist pattern 2a.

In the experiment carried out in this example, the 0.2 μm line & space pattern collapsed in the normal method without heating the rinse liquid. However, as described above, the rinse liquid was heated. In the method of the present invention performed, pattern collapse did not occur.

In addition, the present inventors carried out a resist pattern forming process consisting of the steps shown in FIG. 3 in order to verify still another embodiment capable of improving the crosslinking rate of the resist. That is, the processes of FIGS. 9A to 9D are the same as those of the first and second embodiments. However, as the resist 2, any acid-catalyzed crosslinking resist may be used, and in this embodiment, AZ-PN100 (trade name) manufactured by Hoechst Co. was used, and the film thickness thereof was 0.85 μm. Then, without drying the rinse liquid 5, as shown in FIG.
It was immersed in the acid solution 6. Here, a dilute acetic acid solution was used as the acidic solution 6, but a dilute hydrochloric acid solution, a dilute sulfuric acid solution, or the like can also be used. It is even better to heat the acidic liquid 6. After that, as shown in FIG. 6F, rinsing with water 5a was performed, and finally spin drying was performed to remove the rinse liquid 5a as shown in FIG. 6G to form a resist pattern 2a.

In the experiment conducted in this example, the 0.15 μm line &
The space pattern caused pattern collapse, but the pattern collapse did not occur in the method of the present invention in which the space pattern was immersed in the acidic solution as described above.

On the other hand, the inventors of the present invention formed a resist pattern by using a positive resist composed of naphthoquinone diazide and a novolak resin in order to verify another embodiment capable of improving the crosslinking rate of the resist. Among them, the same processing as in the first to third embodiments is performed up to the rinse processing. However, the above-mentioned positive resist was used as the resist 2, and the film thickness thereof was 1 μm. Then, before the rinse liquid 5 was dried, the entire surface of the resist 2 was irradiated with light including far-ultraviolet light using an Hg-Xe lamp. The irradiation amount was 1 kJ / cm ² . Finally, spin drying was performed to remove the rinse liquid 5 to form a resist pattern 2a.

In the experiment conducted in this example, 0.2 μm was obtained by the usual method in which the far-ultraviolet light was not entirely irradiated.
Although the line & space pattern caused pattern collapse, in the method of the present invention in which the entire surface was irradiated as described above, the irradiation increased the degree of crosslinking of the novolac resin, and the pattern did not occur.

The Young's modulus of the resist 2 before drying the rinse liquid 5 is 10 ⁹ d when the pattern size is 0.15 μm level.
more than yn / cm ² and 5 × 10 ⁹ d at 0.1 μm level
When it was yn / cm ² or more, pattern collapse could be prevented.

[0022]

According to the method of the present invention described in detail above, in the case of a resist pattern, particularly a dense minute resist pattern or a resist pattern having a high aspect ratio, it is possible to prevent pattern collapse between adjacent ones. Therefore, the yield of products manufactured based on the resist pattern formed by the method of the present invention is dramatically improved. still,
When the method of the present invention is used for lithography, light, electron beam,
It can be applied to any lithography such as X-ray and charged particle beam.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a resist pattern forming step according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a resist pattern forming step according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a resist pattern forming process according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional resist pattern forming process.

FIG. 5 is an explanatory diagram showing a typical resist pattern collapse state.

[Explanation of reference numerals] 1 substrate 2 resist 2a resist pattern 3 mask 4 developing solution 5 5a rinsing solution 6 acidic solution

Claims (10)

[Claims] 1. A resist pattern forming method comprising exposing a resist to a desired pattern, developing the resist, and then rinsing and drying the rinse liquid to form a resist pattern. A method for forming a resist pattern, which comprises performing a treatment for increasing the strength of the resist in a liquid during the rinsing or during the rinsing treatment. 2. A resist pattern forming method comprising exposing a resist to a desired pattern, developing the resist, rinsing the resist, and drying the rinse liquid to form a resist pattern. A method for forming a resist pattern, characterized in that a treatment for increasing the degree of crosslinking of the resist is performed in a liquid during or during the rinsing treatment. 3. The resist pattern forming method according to claim 2, wherein when the resist is a negative type resist, the degree of crosslinking of the resist is increased by irradiating the resist with light. The resist pattern forming method according to claim 2. 4. The resist pattern forming method according to claim 2, wherein when the resist is a chemically amplified resist, the cross-linking degree of the resist is increased by raising the liquid temperature to a temperature that promotes cross-linking. Claim 2 characterized by
A method for forming a resist pattern according to the item. 5. The resist pattern forming method according to claim 2, wherein when the resist is an acid-catalyzed crosslinking-accelerating type resist, the degree of crosslinking of the resist is increased by treating in an acidic solution. The method for forming a resist pattern according to claim 2. 6. The method for forming a resist pattern according to claim 5, wherein the crosslinking temperature of the resist is increased by increasing the liquid temperature to a temperature that promotes crosslinking and then treating in an acidic liquid. Item 5. A method for forming a resist pattern according to item 5. 7. The resist pattern forming method according to claim 2, wherein the resist is a positive resist based on a resin having a benzene ring as a base,
3. The base resin is crosslinked by irradiating the resist with ultraviolet light or deep ultraviolet light.
A method for forming a resist pattern according to the item. 8. A resist pattern forming method comprising exposing a resist to a desired pattern, developing the resist, and then rinsing and drying the rinse liquid to form a resist pattern. A method for forming a resist pattern, characterized in that a treatment for increasing the degree of polymerization of the resist is performed in a liquid during or during the rinsing treatment. 9. A resist pattern forming method comprising exposing a resist to a desired pattern, developing the resist, then rinsing and drying the rinse liquid to form the resist pattern.
^A method for forming a resist pattern, which is ⁹ dyn / cm ² or more. 10. The resist pattern forming method according to claim 9, wherein the Young's modulus of the resist is 5 × 10 ⁹ d.
10. The resist pattern forming method according to claim 9, wherein the resist pattern is yn / cm ² or more.